We’ve invested $168 million in an exciting new solar energy power plant being developed by BrightSource Energy in the Mojave Desert in California. Brightsource’s Ivanpah Solar Electric Generating System (ISEGS) will generate 392 gross MW of clean, solar energy. That’s the equivalent of taking more than 90,000 cars off the road over the lifetime of the plant, projected to be more than 25 years. The investment makes business sense and will help ensure that one of the world’s largest solar energy projects is completed.

We need smart capital to transform our energy sector and build a clean energy future. This is our largest investment to date, and we’ve now invested over $250 million in the clean energy sector. We’re excited about Ivanpah because our investment will help deploy a compelling solar energy technology that provides reliable clean energy, with the potential to significantly reduce costs on future projects.

Power towers, which have been successfully demonstrated in the U.S. and abroad at smaller scale, are based on a relatively simple idea. The technology works by using a field of mirrors, called heliostats, to concentrate the sun’s rays onto a solar receiver on top of a tower. The solar receiver generates steam, which then spins a traditional turbine and generator to make electricity. Power towers are very efficient because all those mirrors focus a tremendous amount of solar energy onto a small area to produce steam at high pressure and temperature (up to 1000 degrees F). Think about burning a tuft of grass with a magnifying glass, only multiplied by thousands (or the original application: Archimedes’ heat ray that allegedly used mirrors to burn enemy ships!).

Several large solar projects are in the works in the sunny Southwest (and around the globe), but Ivanpah will be the first solar power tower system of this scale. The Ivanpah Power Tower will be approximately 450 feet tall and will use 173,000 heliostats, each with two mirrors. The project is being constructed by Bechtel, a major engineering firm. Construction began in October 2010, and is projected to finish in 2013.

The Ivanpah project will also be financed by NRG and with clean energy technology loan guarantees provided by the U.S. Department of Energy. We hope that investing in Ivanpah spurs continued development and deployment of this promising technology while encouraging other companies to make similar investments in renewable energy.